BL 9.2-inch Mk I – VII naval gun

The BL 9.2-inch Mk I–VII guns[note 2] were a family of early British heavy breechloading naval and coast defence guns in service from 1881 to the end of World War I. They were originally designed to use the old gunpowder propellants.

Ordnance BL 9.2-inch Mk I–VII gun
Mk VI gun on disappearing mounting at Ben Buckler Gun Battery, Sydney
TypeNaval gun
Coast defence gun
Place of originUnited Kingdom
Service history
In service1881–1918
Used byRoyal Navy
Australian colonies
WarsWorld War I
Production history
VariantsMk I – VII
Specifications
MassMk I & II : 20 tons barrel & breech

Mk III : 24 tons

Mk V–VII : 22 tons[1]
Barrel lengthMk I & II : 230 inches (5,842 mm) bore & chamber (25 calibres)
Mk III–VII : 290 inches (7,366 mm) (31.5 calibres)[1]
Shell380 pounds (172.37 kg)[1]
290 pounds (131.54 kg) (High-angle guns)[2]
Calibre9.2-inch (233.7 mm)
Muzzle velocity2,065 feet per second (629 m/s)[3]
Maximum firing range10,000 yards (9,100 m)[note 1]

History

Mk I and II

British 9.2 inch guns originated from a request by the Admiralty in 1879 for a gun comparable to Krupp's 24 cm (9.45 inch) gun at the time. The Admiralty submitted its request to the Committee on Ordnance, which was considering returning to breech-loading artillery after Britain's brief return to muzzle-loaders in the 1860s and 1870s. A new breech-loading gun with a 9.2-inch (234 mm) bore, firing a 380-pound projectile was calculated to be suitable.[4] A total of 19 Mk I and Mk II guns of 26 calibres were made starting in 1881, but after lengthy delays and modifications they proved unsatisfactory and none made it to sea.

Mk III – Mk VII

The 31.5 calibres versions, Mk III through to Mk VII became the first to be mounted on ships and deployed in general service.

Training drill, 1890s
Forward gun on HMS Australia, 1893

Guns equipped the following ships :

Coast defence gun

Most Mk IV guns and some Mk VI guns were used in coast defences.

In the mid-to-late 1880s successful trials were carried out with RML 9-inch coast-defence guns firing at high angles in order to test the effectiveness of plunging fire on decks of ships. When surplus BL 9.2 inch Mk IV and Mk VI guns became available in the 1890s they were likewise adapted to high-angle carriages, with their obsolete 3-motion breech mechanisms replaced by modern continuous-motion patterns to allow faster loading. Locations included Hawkins Battery near Plymouth and Gibraltar.[5]

The elevation of up to 45° meant that the shell was at risk of slipping back after being rammed forward as only the copper driving band held the shell in place in a BL gun, and they had not been designed to operate at such high angles. The solution adopted was to develop a special high-angle reduced-charge cartridge with a hollow up the centre, through which the gunner inserted a 1+1⁄4-inch-diameter (32 mm) stick about 40 inches long made of beech wood, to prevent the projectile from slipping back before firing. A "light" 290-pound (130 kg) shell was used for high-angle firing, rather than the standard 380-pound (170 kg) shell.[6]

In the late 19th century to early 20th century five Mk IV coast-defence guns were installed at Singapore : two at Fort Connaught on Blakang Mati, one at Fort Siloso on Sentosa Island and two at Fort Pasir Panjang on Singapore Island.[7] Two of these remain at Fort Siloso.

World War I railway gun
Main article: BL 9.2 inch Railway Gun
HMS Iron Duke, a Mk III* or Mk VI gun in action at Maricourt, Battle of the Somme, September 1916

From 1915 onwards Elswick adapted a small number of Mk III, Mk IV and Mk VI guns, and mounted them on railway truck mountings for service on the Western Front in France and Belgium.[8]

Australian service

In the late 1880s and early 1890s the Australian colonies between them ordered 10 barrels and nine carriages for BL 9.2 inch Mk VI 'counter bombardment' disappearing guns:[9]

  • New South Wales : Three went to protect Sydney Harbour, plus an extra barrel. Of these, one went to Ben Buckler Gun Battery, one to Signal Hill Battery, and one to Steel Point Battery. The barrel of the gun that had been installed at Signal Hill Battery survives on public display at the Royal Australian Artillery Museum at North Fort, North Head. The gun and carriage of the Ben Buckler gun were unearthed in 1984 and await restoration.
  • Victoria : Four guns went to Victoria to protect Port Phillip, with two going to Fort Nepean and two going to Fort Queenscliff.
  • South Australia : In 1888, South Australia purchased two guns for what was to be Fort Glenelg to protect Adelaide, South Australia. However, the residents of Glenelg, concerned that they might become a military target, were able to block construction of the Fort and so the guns were never installed. The British government bought them back in 1915.[10][11]

Ammunition

Surviving examples
  1. One Mark I located in Port Royal, Jamaica, on the shores at Fort Charles. Stamped with Mark I 9.2 inch 22 ton gun lying next to its battery and Powder House. Taken out of service after the 1907 earthquake.

See also

Notes
  1. 10,000 yards refers to naval mountings which had limited elevation : Text book of gunnery, 1902. Coast and rail mountings allowed greater elevation and hence range.
  2. i.e. Marks 1 to 7. Britain denoted marks (models) of ordnance using Roman numerals until after World War II.

References
  1. Text Book of Gunnery 1902, Table XII Page 336
  2. Treatise on Ammunition 10th Edition 1915
  3. 380 lb shell, with 164 lb brown prism powder or 53½ lb cordite propellant size 30. Text Book of Gunnery 1902. 175 lb brown powder is quoted for the Mk V gun in Text Book of Gunnery 1887.
  4. Hogg & Thurston 1972, page 164
  5. Hogg & Thurston 1972, page 167
  6. Treatise on Ammunition 10th Edition, published 1915. Pages 77, 142. High-angle cartridges were 44lb 12 oz or 16 lb 1 oz cordite MD, firing a 290-pound shell.
  7. "The Gun Museum. 9.2-inch BL guns". Archived from the original on 11 January 2010. Retrieved 15 July 2010.
  8. Hogg & Thurston 1972, page 168-170
  9. David Spethman, "The Garrison Guns of Australia 1788–1962", published by Ron H Mortensen, Inala, QLD 2008. ISBN 978-0-9775990-8-0
  10. P.A. Richardson, 1987, Fort Glenelg: The Fort that Never was, University of Adelaide.
  11. "Heritage Branch Website - Online Database". Archived from the original on 24 October 2008. Retrieved 18 January 2009.

Bibliography
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